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Part Three: Improving Cow Comfort Through Environmental Strategies
By Dr. Tricia Wood, Technical Services-Ruminant, Lallemand Animal Nutrition
This article is the final in a series of three about heat stress in dairy cattle. Read previous articles here:
When temperatures rise, so do the risks to cow health, productivity, and an operation’s bottom line. While nutrition plays a role, no ration can overcome the effects of poor climate. That’s why environmental heat abatement is the cornerstone of any effective heat stress management plan. This article will focus on practical, proven strategies to cool your barns and protect all groups — from high-producing lactating cows, to often-overlooked dry and transition cows — from the costly impacts of heat stress.
The Case for Heat Abatement
The importance of cooling strategies on dairy farms has been well documented. Heat stress reduces milk yield, impairs milk component production, lowers reproductive efficiency and increases the risk of metabolic disorders.1 While much of the industry’s attention focuses on lactating cows, dry and transition cows experience substantial — and often underappreciated — consequences from heat stress.
Recent data estimates that annual U.S. industry losses attributed to heat stress in dry cows exceed $1.5 billion.2 This is largely driven by reduced milk production in subsequent lactations, elevated metabolic complications and lower calf birth weights. Moreover, maternal heat stress impairs fetal development, reduces passive immunity transfer at birth and decreases lifetime productivity in offspring.3,4 Protecting these groups supports both immediate animal well-being and the long-term profitability of the operation.
It’s a mistake to ignore the dry cow pen when planning heat abatement strategies.”
Best Practices for Environmental Heat Abatement
The goal of heat abatement is to minimize body heat accumulation and enhance cooling through evaporative and convective mechanisms. A combination of direct and indirect cooling methods consistently delivers the best results.5
Proven, actionable strategies you can take today include:
- Install fans and water soakers in high-density animal areas like holding pens, parlor exit lanes, and feed alleys. Fans should provide continuous air movement over resting and feeding areas. Soakers should activate intermittently to wet cows’ backs and promote evaporative cooling.
- Maintain effective cross-ventilation or tunnel ventilation systems to increase air exchange rates and reduce heat pockets within barns.
- Provide a minimum of 3 inches of linear water trough space per lactating cow, and clean water troughs daily. Water intake rises substantially during heat events, making water hygiene critical.6
- Ensure shaded areas are available in outdoor lots and pasture systems to reduce radiant heat exposure and prevent heat buildup.
Feed and Forage Hygiene: A Heat Stress Multiplier
During summer, forage and TMR heating creates an invisible, added heat stress burden. Wild yeasts and spoilage microbes double rapidly above 65°F (18°C), degrading silage and triggering TMR heating. When cows consume aerobically unstable feed during heat stress, rumen function and digestibility suffer, and intake declines subtly, even if feed sorting and refusals appear minimal.
Best practices to maintain summer feed hygiene:
- Feed fresh TMR to prevent heating in the bunk — ideally removing refusals daily.
- Avoid top-dressing fresh TMR on leftover feed.
- Use a proven forage inoculant containing Lactobacillus buchneri 40788 and hilgardii to enhance aerobic stability and reduce microbial spoilage during storage and feedout.5
- Feed more often per day, ideally twice or more, to encourage smaller, more frequent meals and maintain a constant flow of nutrients to the gastrointestinal tract as energy is being directed away and utilized for evaporative cooling during heat events.
- Prioritize feeding during cooler hours (8 p.m. to 8 a.m.) and perform regular TMR push-ups to encourage intake when cows are naturally more comfortable, as well as to limit bunk heating.
- Incorporate an active dry yeast (ADY) probiotic to rations to support healthy rumen function. One strain, known as Saccharomyces cerevisiae CNCM I-1077, when fed at 20 billion CFU/day/head, is research-proven to maintain and actually increase milk production during heat challenges, by increasing rumen pH, balancing rumen microbiota, and reducing exposure to Sub-Acute Ruminal Acidosis (SARA).6
Economic Value of Heat Abatement Investments
The financial incentive for heat abatement infrastructure and management is consistently positive. For every $1 invested in effective heat abatement, see a 3-6:1 return on investment (ROI) due to improved production, increased reproduction and reduced health costs.1
Importantly, these benefits extend beyond current lactating cows to calves and replacement heifers affected by maternal heat stress during the dry period.3,4 Protecting those groups enhances not just present-day profitability, but also herd viability and performance for years ahead.
Stay on the offensive — proactive heat abatement protects both immediate herd performance and future profitability.”
By combining targeted nutritional strategies, a deep understanding of heat stress biology, and effective environmental heat abatement, dairy farms can build a resilient system that protects cow health, supports consistent performance, and minimizes financial losses during the heat season. This holistic approach ensures cows stay cooler, eat better, and produce more — even under challenging summer conditions.
References:
1 St-Pierre, N.R. et al. (2003). Economic losses from heat stress by U.S. livestock industries. J. Dairy Sci., 86(Suppl): E52-E77.
2 Macko, A.R. et al. (2017). How heat stress during the dry period reduces milk yield in the next lactation. Proc. Southwest Nutrition Conference.
3 Monteiro, A.P.A. et al. (2016). In utero heat stress decreases calf survival and performance through the first lactation. J. Dairy Sci., 99:8443–8450.
4 Laporta, J. et al. (2020). Late-gestation heat stress impairs daughter and granddaughter lifetime performance. J. Dairy Sci., 103:7555–7568.
5 Baumgard, L.H. et al. (2014). Feeding and managing cows to minimize heat stress. Tri-State Nutrition Conference.
6Perdomo et al, 2020. Effect of feeding live yeast at two dosages of performance and feeding behavior of dairy cows under heat stress. J. Dairy Sci.103:325-339.
Published Mar 5, 2026 | Updated Mar 18, 2026
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